The shortcut on Mac control option command, which calls up a square colour picker box, has gone bonkers in the new update. The colours in the square are all bleached and out of whack. I will attached screenshots of the before and after.

Yes there seems to be a bug on the Mac side in Photoshop 27.8 causing issues with colors and image artifacts that Adobe is looking into.

In the meantime users report that going to Photoshop 2026>Settings>Technology Previews, unchecking Precise color management for HDR display and restarting Photoshop clears up things for now.